1. Field of the Invention
The present invention relates generally to apparatuses using electricity to cut or vaporize tissue and, more particularly, to an apparatus having both an electrically charged roller and an electrically charged loop for performing fulguration and cauterization.
Benign prostatic hyperplasia is a medical condition where growth of the prostate gland results in a partial occlusion of the lumen of the urethra. The occlusion of the lumen from this benign growth results in a greater pressure requirement for the patient to void, increased frequency of urination, and greater urine retention in the bladder.
One prior art approach for ablating tissue within the lumen of the urethra involves placing both a resectoscope electrode and a cystoscope within the urethra. The cystoscope is used for visualization while high voltage is applied to the resectoscope electrode in order to remove the benign tissue growth from the lumen of the urethra, thus increasing lumen size, reducing the pressure required to void, and increasing the diameter of the stream of urine. This prior art procedure is conventionally referred to as a transurethral resection of the prostate. Although this procedure is somewhat effective, a shortcoming associated with this procedure is bleeding, which often necessitates one or two days of post-operative hospital time for the patient. Additionally, patients on certain types of medication that affect blood clotting abilities are either contraindicated for this medical procedure or have an increased risk due to the bleeding.
Other procedures of the prior art for treating benign prostatic hyperplasia have been developed for at least partially avoiding the problem associated with bleeding. These procedures include laser, microwave, radio frequency, and thermal abrasion. Each of these procedures presents its own set of complications and shortcomings. One prior art procedure for treating benign prostatic hyperplasia involves the ablation of prostatic tissue through vaporization using a high energy electrical current, which passes through a rollerball placed within the lumen of the urethra and into the electrically grounded patient. The procedure, which is commonly referred to as fulguration, can be implemented using the prior art apparatus illustrated in FIG. 1. The insulated probe 10 comprises a partially insulated metallic structure, a conducting rollerball 12, and a cylindrical housing 14. Electric current is supplied to the conducting rollerball 12 from a power source through the proximal end 18 of insulated wire, and through two insulated wires 20.
The two insulated wires 20 are joined together by a non-insulated portion of wire, which forms an axis of rotation for the conducting rollerball 12. When the electrical current is applied to the conducting roller ball 12 via the proximal end 18, irrigation fluid is delivered from the cylindrical housing 14 via one of the apertures 16. One of the other two apertures 16 typically accommodates an optical fiber for viewing the ablative site, while the remaining aperture 16 accommodates a light source optical fiber. Electrical current supplied to the conducting rollerball 12 arcs from the conducting rollerball 12 into the tissue within the urethra that comes into contact with the conducting rollerball 12. The electrical spark from the conducting rollerball 12 to the tissue vaporizes the tissue. The irrigation fluid from the apertures 16 includes a non-ionic fluid, which is continuously flushed through the cavity and over the device during the vaporization process. The rolling motion of the conducting rollerball 12 is useful for vaporizing tissues in body cavities, such as the endometrium.
Another prior art device, illustrated in FIG. 2, is similar to the insulating probe 10 of FIG. 1, with the exception of the two cylinders 24 used in place of the conducting rollerball 12. This double cylinder design may in some instances improve ablation and keep tissue from attaching to the cylinders 24, thus increasing the efficiency of the vaporization process.
These prior art apparatuses suffer because of generation of gas caused during the ablation process, the difficulty in removing tissue flaps resulting from the ablation process, and inefficiencies in the design of the conducting rollerball or cylinder. As current passes from the conducting rollerball 12 of the apparatus of FIG. 1, or from the conducting cylinder 24 of the apparatus of FIG. 2, into the tissue to be ablated, tissue is vaporized. This vaporization of tissue presents a potential hazard, resulting from airborne viruses that may exist in gas bubbles generated by the vaporization process. Any viruses within these gas bubbles will be released into the operating room when the vaporization gas is flushed from the bladder. Gas generated from the vaporization procedure additionally obscures the surgical field, as viewed through the cystoscope. The narrow field of view provided by the cystoscope can be nearly totally obscured by the gas bubbles generated by the vaporization process. A need for a clear field of view is particularly important at the distal and proximal ends of the prostate, where urethral and bladder sphincters controlling continence are present. The surgeon may accidentally vaporize too much tissue when the limited view provided by the cystoscope is obstructed with gas bubbles. This vaporization of too much tissue may significantly damage the sphincters and result in incontinence. A need has thus existed in the prior art for an apparatus which can safely route these gas bubbles away from the field of view of the cystoscope to thereby reduce the likelihood of damaging sphincters, for example. Additionally, such a routing means should route these gas bubbles into a safe receptacle, to thereby prevent introduction of any airborne viruses into the operating room.
In addition to gas bubbles, tissue flaps created during the fulguration (ablation) process tend to obstruct the limited field of view of the cystoscope, as well. Prior art devices comprising only a conducting rollerball 12 or a conducting cylinder 24 are not able to efficiently remove these flaps of tissue, since the flaps of tissue are not anchored by surrounding tissue and have a tendency to move as they are manipulated by the rollerball or cylinder. The existence of these flaps of tissue, and the associated difficulty in removing them, results in an uneven removal of tissue by the rollerball or cylinder. Even tissue, such as the urethral sphincter, may be undesirably ablated as the result of the existence of flaps of tissue in the area. A need has thus existed in the prior art for an apparatus that can efficiently remove flaps of tissue generated during the fulguration process.
Still another problem associated with the prior art stems from intrinsic limitations in the designs of the rollerballs or cylinders of the prior art. These cylinders commonly comprise smooth surfaces, which are prone to accumulation of tissue and carbon deposits. Additionally, these smooth surfaces do not provide an optimal amount of friction and, thus, some slippage or skidding of these prior art rollers often occurs. A need has existed in the prior art for conducting rollers which have traction and which exhibit better cleaning and operating properties.